A control system (engine starting control system) for starting an engine is disclosed in JP-A-8-133016, for example. The control system is used as an immobilizer for protecting a vehicle from being stolen. Specifically, a verification ID is stored in a key or a wireless communication portable device taken by a user of the vehicle. The immobilizer authenticates the verification ID of the portable device with respect to the master ID of the vehicle, so that engine starting is allowed in accordance with a verification result between the ID of the portable device and the master ID of the vehicle.
In this engine starting control system, when an ID verification is rejected, an engine controller becomes in a starting prohibiting condition (immobilizer set condition), so that engine starting is prohibited by an unauthorized person. Here, the vehicle has an immobilizer controller, which is a component different from the engine controller. The immobilizer controller transmits a control command for prohibiting engine from being started. The engine controller controls engine starting in reference to a prohibition setting signal, which prohibits engine starting, and a prohibition releasing signal, which releases the starting prohibiting condition, transmitted from the immobilizer controller.
When the immobilizer controller releases the starting prohibiting condition, the engine controller accepts a starting operation performed by a driver, so that the engine controller starts the engine. However, when a cranking is performed in engine starting, a starter imposes a heavy load against a battery, and battery voltage temporarily largely decreases. As a result, the immobilizer controller may be reset, and a verification result of ID is also reset, in general. The prohibition setting signal, which is once released, may be reset to be the prohibition setting condition. In this condition, the engine controller may stop the engine, and engine starting may not be smoothly performed.
The following two methods may be conceivable to solve the above problem.
First, a routine for releasing the prohibition setting condition is reexecuted after returning to a step, in which the ID verification is performed.
Second, a data backup is performed to store information, which indicates completion of releasing the prohibition setting condition, in a non-volatile memory after completing the processing for releasing the prohibition setting condition to enable recognizing the releasing of the prohibition setting condition, even after resetting.
However, in recent years, complexity of an algorithm of the ID verification increases for enhancement of security. Accordingly in the first method, the ID reverification may take long, and engine restarting may not be smoothly performed due to the ID reverification.
When the engine starting control system adopts a mechanical key system, the key position is fixed during operation of the vehicle, and an ID can be transmitted from a transponder of the key inserted into a key cylinder, so that transmittance of the ID can be regularly retried, for example. However, in recent years, the engine starting control system adopts a method using a wireless communication from a wireless communication portable device to perform ID verification. In this system, the portable device is not necessarily located near a receiver on the side of the vehicle for the ID verification, after a driver enters into the vehicle. Accordingly, in this system, it may be impossible to perform ID reverification.
By contrast, in the second method, the releasing of the prohibition setting condition may be recognized by referring the back up data in the non-volatile memory without performing ID reverification, thereby proving the problem in the first method. However, a period before engine starting after releasing the prohibition setting condition is short, in general. Therefore, the immobilizer controller may be reset due to cranking before performing the data backup of the releasing of the prohibition setting condition in the non-volatile memory. In this case, it is impossible to recognize the releasing of the prohibition setting condition in accordance with the back up data.